What is the Difference Between Mismatch Repair and Nucleotide Excision Repair?

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Mismatch repair and nucleotide excision repair are two distinct DNA repair mechanisms that handle different types of DNA damage. Here are the main differences between them:

Mismatch Repair:

  1. Corrects base-base mismatches and small loops that occur during DNA replication.
  2. Occurs right after new DNA has been made.
  3. Involves a protein complex that recognizes and binds to the mispaired base, followed by cutting the DNA near the mismatch and removing the incorrect nucleotide and a surrounding patch of DNA.
  4. Does not operate on bulky adducts or major distortions to the DNA helix, focusing mostly on subtle helical distortions caused by misincorporated nucleotides.

Nucleotide Excision Repair:

  1. Removes pyrimidine dimers and other helix-distorting lesions.
  2. Detects and corrects types of damage that distort the DNA double helix, such as bases modified with bulky chemical groups or damage caused by UV radiation.
  3. Involves the removal of a 12-24 nucleotide section when the DNA is warped.
  4. Handles bulky adducts or major distortions to the DNA helix.

In summary, mismatch repair focuses on correcting base pairing mistakes that occur during DNA replication, while nucleotide excision repair deals with DNA damage that results in distortions to the DNA double helix. These two repair mechanisms operate on different types of DNA damage and use distinct processes to restore the genetic material.

Comparative Table: Mismatch Repair vs Nucleotide Excision Repair

Mismatch repair and nucleotide excision repair are two mechanisms that occur in the cell to rectify DNA damage. Here are the key differences between them:

Feature Mismatch Repair Nucleotide Excision Repair
Repair Type Corrects errors Removes large, bulky
that occur during DNA synthesis adducts and major distortions to the DNA helix
Double-Strand No Yes
Structure Conserved Not highly conserved
Gap Filling DNA polymerase III DNA polymerase I

Mismatch repair corrects errors that occur during DNA synthesis, while nucleotide excision repair removes large, bulky adducts and major distortions to the DNA helix. Mismatch repair is highly conserved, but nucleotide excision repair is not highly conserved. In mismatch repair, the incorrect nucleotide is excised and replaced with the correct nucleotide by the concerted action of DNA polymerase III. In nucleotide excision repair, a short, single-stranded stretch of the affected DNA strand is removed, and the gap is filled in by a DNA polymerase.